1. Field of the Invention
The present invention relates to an auto-tensioner for applying a predetermined tension to an endless belt or an endless chain by placing a rotor into resilient abutment against the endless belt or the endless chain.
2. Description of the Prior Art
An auto-tensioner is conventionally known, for example, from Japanese Patent Application Laid-Open No. 7-286646. The known auto-tensioner is designed so that an eccentric pulley support is swingably carried on an outer periphery of a cam shaft through a braking member made of a synthetic resin, and a pulley rotatably supported on an outer periphery of the pulley support, is brought into pressure contact with the endless belt by the resilient force of a spring. The action of the pulley support due to a variation in tension of the endless belt is inhibited by the friction force generated between the cam shaft and the pulley support by the braking member.
However, the above conventional auto-tensioner suffers from the problem that if the temperature of the braking member is raised by the friction heat generated by the sliding movement of the braking member on the pulley support, scorching, hardening, cracking or the like is produced, resulting in a reduction in durability of the auto-tensioner.